Given an n-vertex graph G and a function f : V (G) → {0, . . . , n-1}, an f-factor is a subgraph H of G such that degH(v) = f(v) for every vertex v ϵ V (G);we say that H is a connected f-factor if, in addition, the s...
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The recent increase of interest in the graph invariant called tree-depth and in its applications in algorithms and logic on graphs led to a natural question: is there an analogously useful "depth" notion als...
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Vertex deletion problems ask whether it is possible to delete at most k vertices from a graph so that the resulting graph belongs to a specified graph class. Over the past years, the parameterized complexity of vertex...
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In the generalized truncation construction, one replaces each vertex of a k-regular graph Γ with a copy of a graph Υ of order k. We investigate the symmetry properties of the graphs constructed in this way, especial...
Recently, a new way of avoiding crossings in straight-line drawings of non-planar graphs has been introduced. The idea of partial edge drawings (PED) is to drop the middle part of edges and rely on the remaining edge ...
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We consider the following problem of labeling points in a dynamicmap that allows *** are given a set of feature points in the plane labeled by a set of mutually disjoint labels, where each label is an axis-aligned rec...
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A modulator of a graph G to a specified graph class H is a set of vertices whose deletion puts G into H. The cardinality of a modulator to various graph classes has long been used as a structural parameter which can b...
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Kernelization investigates exact preprocessing algorithms with performance guarantees. The most prevalent type of parameters used in kernelization is the solution size for optimization problems;however, also structura...
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The derived datatype mechanism is a powerful, integral feature of the Message-Passing Interface (MPI) for communicating arbitrarily structured, possibly non-consecutive and non-homogeneous application data. MPI define...
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ISBN:
(纸本)9781509021413
The derived datatype mechanism is a powerful, integral feature of the Message-Passing Interface (MPI) for communicating arbitrarily structured, possibly non-consecutive and non-homogeneous application data. MPI defines a set of derived datatype constructors of increasing generality, which allows to describe arbitrary data layouts in a reasonably compact fashion. The constructors may be applied recursively, leading to tree-like representations of the application data layouts. Efficient derived datatype representations are required for MPI implementations to efficiently access and process structured application data. We study the problem of finding tree-like representations of MPI derived datatypes that are optimal in terms of space and processing cost. More precisely, we consider the so-called MPI Type Reconstruction Problem of determining a least-cost tree-like representation of a given data layout for a given set of constructors. In an additive cost model that accounts for the space consumption of the constructors and lower-bounds the processing costs, we show that the problem can be solved in polynomial time for the full set of MPI datatype constructors. Our algorithm uses dynamic programming and requires the solution of a series of shortest path problems on an incrementally built, directed, acyclic graph.
We study a boundary labeling problem, where multiple points may connect to the same label. In this new many-to-one model, a horizontal backbone reaches out of each label into the feature-enclosing rectangle. Feature p...
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